I use the Zulu's in the Dash8. Got them on ebay for 700 bucks about a year ago, virtually band new. Warranty carried over too.

I absolutely LOVE them! They work great. My ears used to ring after a flight, now they don't.

One thing I did do however is take off the original head pad and purchased a brand new David Clark "super soft" H-10 head pad. Here's a picture: David Clark Super Soft Head Pad - MyPilotStore.com The new pad fits the headset fine and makes the headset much more comfortable. I doubt most would have an issue with the original pad, but it gives you hot spots try this - it was night and day better for me.

The feature I like the most is that when there is no radio chatter, or talking between pilots, the Zulu will cut out all the background hiss and give pure silence. To achieve this one must turn the volume on the headset up to about .75 or higher and then use your comm panel to bring the volume back down to a comfortable level. If the volume on the headset is set below the .75 threshold it doesn't seem to counter the hiss. Took awhile to figure this out.

I've tried the bose X and the QC-15 uflymike. To me they don't even compare to the Zulu's in my opinion.

I haven't really used the blue-tooth except to call my dad once in my living room. Seemed to work fine. Voice quality was excellent. Oh that reminds me the sound quality in the plane was remarkably better than I'd ever heard in my other run of the mill headsets. Makes a long flight quite a bit more pleasant and counters fatigue quite a bit I think.